STMicroelectronics LD1117ADT12TR

Overview

LD1117ADT12TR from STMicroelectronics is a 1.2 V fixed-output, low-dropout linear voltage regulator in DPAK (TO-252) package, delivering up to 1 A output current with 1.15 V typical dropout at 1 A and ±2% output voltage tolerance at 25 °C. It features internal current and thermal limiting, requires only a 10 µF output capacitor for stability, and operates across 0 °C to 125 °C junction temperature - used in embedded power rails for microcontrollers and sensors.

For engineers reviewing the LD1117ADT12TR datasheet, LD1117ADT12TR pinout, LD1117ADT12TR application, or LD1117ADT12TR equivalent, key selection criteria include dropout voltage at full load, quiescent current under no-load conditions, thermal resistance (R_thJA = 100 °C/W), and compatibility with standard 1.2 V logic supply domains in industrial control and IoT edge nodes.

Technical Context

The LD1117ADT12TR uses an NPN pass transistor architecture to achieve low dropout while maintaining high PSRR (80 dB typ. at 120 Hz) and low output noise (100 µV RMS, 10 Hz–10 kHz). Its reference voltage is internally trimmed to 1.2 V ±2%, with line regulation of 1–6 mV over input range 2.75–10 V and load regulation of 1–10 mV from 0–1 A.

Thermal protection activates at junction temperatures exceeding 125 °C, and current limiting engages at ~1.2 A. The device supports stable operation with ceramic or electrolytic 10 µF output capacitors and does not require an input capacitor under most conditions.

Key Specifications

Pinout & Package

DPAK (TO-252) package with exposed thermal pad connected to VOUT; optimized for surface-mount thermal performance (R_thJA = 100 °C/W, R_thJC = 8 °C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output LDO regulator applications.

Compared with TLV1117-12CDR and MCP1700T-1202E/TT, the LD1117ADT12TR uniquely balances 1 A capability, 1.15 V dropout, and 80 dB PSRR - making it optimal for industrial and IoT systems requiring both high current and high noise immunity at 1.2 V.

Availability

LD1117ADT12TR is available at Aetrix Electronics and suitable for industrial automation, IoT edge node design, and medical wearable instrumentation requiring stable component supply and long-term manufacturability.

Supply support for LD1117ADT12TR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets.

The LD1117A series targets cost-sensitive, high-reliability linear regulation needs in industrial control, power management ICs, and embedded systems where simplicity, thermal robustness, and proven field reliability are critical.

FAQ

What is the minimum input voltage required for stable 1.2 V output at 1 A load?

The LD1117ADT12TR requires a minimum input voltage of 2.35 V (1.2 V + 1.15 V dropout) to maintain regulation at 1 A and 25 °C. At elevated temperatures or higher current, the dropout increases to 1.30 V, so 2.5 V input is recommended for margin across full operating conditions.

Can this regulator be used with ceramic output capacitors?

Yes - the LD1117ADT12TR is stable with ceramic capacitors ≥10 µF and ESR as low as 10 mΩ. Unlike older LDOs, it does not require minimum ESR, eliminating the need for series resistors or hybrid capacitor solutions.

Is the thermal pad electrically isolated in the DPAK package?

No - the exposed thermal pad on the LD1117ADT12TR DPAK package is internally connected to the VOUT pin. It must be soldered to a copper pour tied to the 1.2 V output net to ensure proper thermal conduction and electrical integrity.

Does this part support reverse-voltage protection?

No - the LD1117ADT12TR lacks built-in reverse-voltage protection. If input polarity reversal is possible, an external series Schottky diode (e.g., 1N5819) must be added between the input source and IN pin to prevent damage.